Do not start StartupWatchDogThread as results are just discarded.

Currently even if hangs are detected they will not be reported. See https://crbug.com/440885.

Furthermore we are actively developing the replacement to this solution which aims to
eliminate the false positives that caused the deactivation in the first place.

Bug: 1034046
Change-Id: Ifc29ae961bc8b75d04fe6bdc6e205c72a763a9da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2042292Reviewed-by: François Doray <fdoray@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Oliver Li <olivierli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739194}

chrome/browser/chrome_browser_main.cc

@@ -1532,14 +1532,6 @@ int ChromeBrowserMainParts::PreMainMessageLoopRunImpl() {
   language_usage_metrics::LanguageUsageMetrics::RecordApplicationLanguage(
       browser_process_->GetApplicationLocale());
 
-// StartupTimeBomb is disabled on Android, see https://crbug.com/366699.
-#if !defined(OS_ANDROID)
-  // Start watching for hangs during startup. We disarm this hang detector when
-  // ThreadWatcher takes over or when browser is shutdown or when
-  // startup_watcher_ is deleted.
-  startup_watcher_->Arm(base::TimeDelta::FromSeconds(600));
-#endif  // !defined(OS_ANDROID)
-
 // On mobile, need for clean shutdown arises only when the application comes
 // to foreground (i.e. MetricsService::OnAppEnterForeground is called).
 // http://crbug.com/179143